What is "early media" in SIP?

Early media in SIP (Session Initiation Protocol) refers to the media that is transmitted before the recipient answers the call. This concept is crucial in scenarios where information such as ringback tones, advertisements, or other media is played to the caller while the call is still being established. For example, when a caller dials a number, they may hear ringing or a recorded message before the recipient picks up; this is classified as early media.

This capability allows service providers to offer a richer call experience right from the initiation of the call, enhancing user engagement even during the call setup phase. Early media plays a significant role in ensuring that users have a seamless experience without them needing to wait for an answer to start receiving media content. It's an essential feature in various applications, such as interactive voice response (IVR) systems and call routing services, helping to keep users engaged while their call is being processed.